I have to do this project for school (simple question, please help)?

The numbers are relative to the maximum decibels of your hardware. Thus if your speakers set to their current volume and push to the full potential at that level is 80 decibels, then -34 decibels would be 80-34 decibels. Your going to have to careful be cause different speakers sets are going to have different max decibels, and this is relative to the volume levels you have selected.